Since I've gotten a number of questions about this, I thought I'd answer them here ...
In a nutshell, Ronda trained with Lucia Rijker before her last fight. Ms. Rijker is a boxing legend and all around good person.
After Ronda's fight, one of the boxers Lucia trains, Diana Prazak (who was also one of Ronda's training partners), fought for the world boxing title - and won it. During that fight, her opponent, Frida Wallberg, was knocked out, suffered a brain hemorrhage and operated on the next day.
Lucia knew that Frida had a young child and would need assistance following her injury. Her original idea was to do a clinic to raise money, but Ronda had to take off to Bulgaria for a movie and could not take part.
So ... Ronda asked Jessica, who runs the Armbar Nation website to help out. You can read about it in detail here. (Jessica has been on eBay practically since it started, so she was a natural person to ask.)
The short version is that Jessica had some t-shirts made up to be auctioned off for this and Ronda autographed all of them. I know that the designs with Ronda's signature printed on them are ONLY available for fundraising like this. So, not only can you not buy them autographed elsewhere, you can't buy them period. Once this got started, other people, also donated autographed merchandise.
You can see the auction site here.
You can also click on a link just to donate.
I wish Ms. Wallberg a speedy recovery and hope that the funds raised make it easier for her to spend more time relaxing at home with her daughter and less time worrying about expenses.